The MAX98375 is a high-efficiency Class D audio amplifier designed to deliver a high-quality audio experience with a 3.2W output power. This component is particularly suitable for portable and battery-powered applications due to its low quiescent current draw. Common applications include wireless speakers, mobile phones, laptops, and other portable audio devices where space and power efficiency are critical.
This circuit is a multi-sensor data acquisition system that uses a Nucleo WB55RG microcontroller to interface with a digital temperature sensor (TMP102), a pulse oximeter and heart-rate sensor (MAX30102), and a 0.96" OLED display via I2C. Additionally, it includes a Sim800l module for GSM communication, powered by a 3.7V LiPo battery.
Open Project in Cirkit Designer
This circuit features an ESP32-WROOM-32UE microcontroller as the central processing unit, interfacing with a variety of sensors and modules. It includes a MAX30100 pulse oximeter and heart-rate sensor, an MLX90614 infrared thermometer, an HC-05 Bluetooth module for wireless communication, and a Neo 6M GPS module for location tracking. All components are powered by a common voltage supply and are connected to specific GPIO pins on the ESP32 for data exchange, with the sensors using I2C communication and the modules using UART.
Open Project in Cirkit Designer
This circuit features a SparkFun ESP32 Thing Plus microcontroller interfaced with an Adafruit ICM20948 9-axis motion sensor via an Adafruit TXB0104 4-channel bi-directional level shifter. The ESP32 reads data from the ICM20948 sensor, calculates orientation angles such as pitch, roll, yaw, and azimuth, and outputs these values to the serial monitor. The level shifter ensures compatibility between the 3.3V logic levels of the ESP32 and the 1.8V logic levels required by the ICM20948.
Open Project in Cirkit Designer
This circuit is a multi-sensor data acquisition system using an ESP32 microcontroller. It integrates various sensors including a BH1750 light sensor, BMP280 pressure sensor, DS3231 RTC, and DS18B20 temperature sensor, and displays data on a series of MAX7219 8x8 LED matrices. The system is powered via USB and includes a green LED indicator.
Open Project in Cirkit Designer| Pin Number | Pin Name | Description |
|---|---|---|
| 1 | PVDD | Power supply for the output stage. |
| 2 | GND | Ground reference for the amplifier. |
| 3 | IN+ | Positive audio input. |
| 4 | IN- | Negative audio input. |
| 5 | GAIN | Gain selection input. |
| 6 | SD | Shutdown control input (active low). |
| 7 | BCLK | Bit clock input for digital audio data. |
| 8 | LRC | Left/Right clock input for digital audio data. |
| 9 | DIN | Digital audio data input. |
| 10 | BST | Bypass pin for the internal boost converter. |
Power Supply: Connect a clean power supply to the PVDD pin (1) and ground to the GND pin (2). Ensure the voltage is within the specified range (2.5V to 5.5V).
Audio Input: For analog input, connect the audio source to IN+ (3) and IN- (4). For digital audio, use BCLK (7), LRC (8), and DIN (9) to interface with the audio source.
Gain Setting: The GAIN pin (5) can be used to set the amplifier gain. Refer to the datasheet for the appropriate resistor values to achieve the desired gain.
Shutdown Control: The SD pin (6) can be used to put the amplifier into a low-power shutdown mode when driven low.
Speaker Connection: Connect the speaker between the OUT+ and OUT- pins, ensuring the speaker's impedance is within the supported range.
Q: Can the MAX98375 be used with a mono speaker? A: Yes, the MAX98375 can be configured for mono output.
Q: What is the recommended power supply filtering? A: A low-ESR ceramic capacitor (typically 1µF) should be placed as close as possible to the PVDD and GND pins.
Q: How do I put the MAX98375 into shutdown mode? A: Pull the SD pin low to enter shutdown mode. When the pin is left floating or driven high, the amplifier is active.
Below is an example of how to use the MAX98375 with an Arduino UNO for I2S audio output.
#include <Arduino.h>
#include <Wire.h>
#include <I2S.h>
// Define the I2S pins for the Arduino UNO
#define I2S_BCLK 13
#define I2S_LRC 10
#define I2S_DIN 11
#define I2S_SD 9 // Shutdown pin for the MAX98375
void setup() {
// Initialize I2S with the desired audio settings
I2S.begin(I2S_PHILIPS_MODE, 44100, 16);
// Set the shutdown pin to output and turn off the amplifier
pinMode(I2S_SD, OUTPUT);
digitalWrite(I2S_SD, LOW);
}
void loop() {
// Example: Generate a 1kHz sine wave (not a complete implementation)
int sample;
for (int i = 0; i < 44100; i++) {
sample = 32767 * sin(2 * PI * 1000 * i / 44100);
I2S.write(sample);
}
// To turn on the amplifier, set the shutdown pin high
digitalWrite(I2S_SD, HIGH);
// Your audio processing code goes here
// To turn off the amplifier, set the shutdown pin low
digitalWrite(I2S_SD, LOW);
}
Note: This code is for illustrative purposes and may require additional setup and configuration depending on the specific application and audio source. Always refer to the MAX98375 datasheet and the Arduino I2S library documentation for detailed information and advanced usage.